This project seeks to clarify both the normal function and the pathophysiology of the substantia nigra. Present experiments include (A) Behavioral effects of electrolytic and 6-hydroxydopamine lesions of the substantia nigra: electrolytic lesions cause contralateral rotation in rats; (B) Metabloic effects of 6-hydroxydopamine lesions of the substantia nigra in rats: lesions of ascending dopaminergic pathways decrease forebrain glucose uptake; (c) Chronic, single-unit recording in substantia nigra in trained, behaving monkeys.